This invention relates to a structure of a discharge electrodes having pin-shaped electrodes, and more particularly to a structure of a discharge electrode in which the pin-shaped electrodes will not corrode and in which a stable glow discharge can be accomplished.
In the prior art, a discharge electrode is known with a structure having a large number of pin-shaped electrodes embedded in an insulating base plate.
For the purpose to obtaining homogeneous glow discharge, to render less resistance to gas flow, and further, to form a compact electric discharge electrode, generally, this pin-shaped electrode is constructed to be thin and to protrude from an insulating base place by a comparatively small amount.
However, in such case when a negative glow extends up to the contact portion between the pin-shaped electrode which is a conductor and the base plate which is an insulator, a large electric field occurs near the bottom of the pin-shaped electrode, and the pin-shaped electrode receives a strong electrochemical reaction near its bottom, and thus it has been observed that it is corroded near the bottom.
This corrosion gradually thins down the bottom of the pin-shaped electrode, and there are cases when it breaks the pin-shaped electrode near the bottom.
Also, in the conventional discharge electrode, since a large electric field is caused near the bottom of the pin-shaped electrode as described above, there is a tendency to transfer a glow discharge into an arcing discharge.